1. Field of the Invention
A phase changing device for light using a ferroelectric liquid crystal (FLC) spatial light modulator (SLM).
2. Description of the Related Art
There are many devices currently used to modulate the two-dimensional phase distributions to a beam of light image. SLMs are especially suitable for optical signal processing applications, and there are many SLMs that can alter the two-dimensional phase distribution of a light beam. However, many of these devices also alter either the amplitude or the polarization of the beam as well. Those that, in certain implementations, can preserve the polarization and amplitude are typically slow; e.g., 1/100 seconds frame speed for parallel aligned nematic liquid crystal.
For correcting aberrated images and for propagation of light beams through aberrating media, deformable mirrors and segmented mirrors have been used to modulate the two-dimensional phase distribution. Both are expensive, complicated, heavy, and slow because they require mechanical actuators. Mechanical means are more subject to failure and thus less reliable. SLMs can also be used to correct for aberrations but their speed limits the bandwidth of the aberrations that they can correct for.
Presently, surface stabilized FLC SLMs are used in a binary mode but have rapid response times of less than 100 microseconds. Even in the binary mode, they typically alter amplitude and/or polarization as well as phase. Some devices have been constructed that use FLC in such a way as to get an analog response. However, these devices use FLC in ways that require processing that is considerably less developed than surface stabilization.